The present invention relates to an apparatus for inspecting a liquid crystal display panel mainly for use in a manufacturing process for a liquid crystal display device.
In the manufacturing process for a liquid crystal display device, before driver ICs are mounted onto a liquid crystal display panel, the liquid crystal display panel is inspected for pixel defects, insufficient or uneven color, luminance and the like by lighting a liquid crystal panel substrate with liquid crystal sealed therein. In an inspection apparatus for use in the inspection, light from a light source is irradiated onto the liquid crystal display panel to inspect a transmission characteristic thereof. Such inspection is called a lighting inspection, a cell inspection or a panel inspection, which is called a lighting inspection hereinbelow.
The foregoing lighting inspection is a visual inspection, an automatic inspection using a measuring apparatus and the like, which are common in that the light from the light source is irradiated onto the liquid crystal display panel to inspect the transmission characteristic thereof.
A lighting inspection apparatus used for a conventional lighting inspection is described, for example, in the gazette of Japanese Patent Laid-Open No. Hei 4 (1992)-248435 or the gazette of Japanese Patent Laid-Open No. Hei 7 (1995)-325009. Such a conventional lighting inspection apparatus is used for performing an inspection by use of a light source equivalent to a backlight of a usual liquid crystal display device. For the backlight of the inspection apparatus, a xenon lamp or a fluorescent lamp has been used. Advantages of the xenon lamp are that the luminance is even and high, stability is high, a size is small and so on. Conversely, disadvantages thereof are that lifetime is short and costs of a control power source and of the same lamp are high. Meanwhile, for the fluorescent lamp, a straight fluorescent lamp has been used. As a structural nature thereof, light from both ends of the fluorescent lamp is dark. In this case, in order to prevent regions of the liquid crystal display panel from being darkened, onto which the light from the both ends is irradiated, a fluorescent tube longer than a size of the panel to be inspected must be used, thus an optical system of the inspection apparatus has been enlarged, leading to enlargement of the inspection apparatus itself.
As described above, for the backlight of the lighting inspection apparatus, the xenon lamp or the fluorescent lamp has been used. In the case of using the xenon lamp, there has been a problem that a cost for common use is high though the performance is high. In the case of using a fluorescent lamp, there has been a problem that the inspection apparatus is enlarged.
The present invention was made with the foregoing problems in mind. A first object of the present invention is to realize an inspection apparatus using a small backlight constituted of a dimmer plate as well as a fluorescent lamp, thus to miniaturize the inspection apparatus for a display panel. A second object of the present invention is to propose an inspection method for a display panel, which uses a dimmer plate autonomously adjusting light.
In order to achieve the foregoing objects, according to a first aspect of the present invention, there is provided an apparatus for inspecting a display panel, comprising: a support structure disposing thereon a display panel to be inspected;
a light source; and
a dimmer plate with a characteristic modulating a light transmission characteristic in accordance with an intensity of light incident thereonto, the dimmer plate being disposed between the support structure and the light source,
wherein light emitted from the light source is made to transmit through the dimmer plate, then made incident onto the display panel disposed on the support structure.
In order to simplify a structure of the apparatus, a second aspect of the present invention is characterized in that, in a constitution of the first aspect, the dimmer plate modulates the light transmission characteristic in accordance with an intensity of an ultraviolet ray incident thereonto and has a reversible photochromic property.
In order to miniaturize the apparatus, a third aspect of the present invention is characterized in that, in the constitution of the first aspect, a fluorescent light emitting tube made of a bent glass tube is provided as the light source.
In order to make even brightness on a surface to be inspected, a fourth aspect of the present invention is characterized in that, in the constitution of the first aspect, a light diffusion plate is disposed between the dimmer plate and the display panel to be inspected.
According to a fifth aspect of the present invention, there is provided a method for inspecting a display panel, said method comprising the steps of:
disposing a display panel to be inspected on a support structure; emitting light from a light source;
making the light emitted from said light source incident onto a dimmer plate, and modulating a light transmission characteristic in accordance with an intensity of the incident light, thus controlling a quantity of light transmitted through the dimmer plate; and
making the transmitted light incident onto the display panel to be inspected, the transmitted light having the controlled quantity.
A sixth aspect of the present invention, which relates to an optical route, is characterized in that, in the method of the fifth aspect, the transmitted light having the controlled quantity is diffused, and the diffused light is made incident onto the display panel to be inspected.
A seventh aspect of the present invention, which relates to a method for utilizing a dimmer plate, is characterized in that, in the method of the fifth aspect, the step of controlling a quantity of transmitted light modulates the light transmission characteristic in accordance with an intensity of an incident ultraviolet ray and utilizes a reversible photochromic property.
An eighth aspect of the present invention, which relates to a concrete inspection method, in the method of the fifth aspect, further comprises the step of: comparing a transmission intensity of light detected after being transmitted through the display panel and a predetermined transmission intensity of light in a standard sample with each other.